versión impresa ISSN 0365-2807
OPAZO A., José Domingo y RAZETO M., Bruno. Effects of different potassium fertilizers on foliar content of nutrients, yield and fruit quality in orange trees cv. Valencia. Agric. Téc. [online]. 2001, vol.61, n.4, pp. 470-478. ISSN 0365-2807. http://dx.doi.org/10.4067/S0365-28072001000400009.
The orange (Citrus sinensis (L.) Osbeck) has high potassium requirements. Nutritional studies in Chile have identified orange orchards with foliar contents below the critical level (7.0 g kg-1). The objectives of this study were to evaluate the potassium fertilizers KCl, KNO3, K2SO4 and K-MgSO4 (double salt of potassium and magnesium) and to determine their effects on fruit quality and yield after three years of annual applications. Eighteen-year-old orange trees (cv. Valencia) grown on La Rosa series soil classed as Mollisol were used. Conventional furrow irrigation with three furrows between the rows was employed. The initial average leaf K concentration was 5.7 g kg-1, which corresponds to a low level. The available K level in the soil was medium, from 0 to 20 cm in depth, and low, from 20 to 40 cm. The foliar K content increased in the second year in the KNO3 and K2SO4 treatments and in the third year in all the treatments with regard to the control. The highest K concentration was obtained with KNO3 (6.8 g kg-1). K-MgSO4 increased Mg concentration from a low (2.1 g kg-1) to an optimum level (2.6 g kg-1). KCl raised the content of foliar chloride from 0.11 to 0.15 g kg-1. No increment occurred in fruit yield but fruit size did increase. Treatments with potassium also increased juice acidity.
Palabras clave : potassium; orange tree; foliar analysis; fruit size.